We're looking to implement two-way authentication with client certificates for a privileged subset of our application users. The idea will be that if a certificate is detected the user will be asked for an additional password/PIN and that will be used to verify the certificate and user. Ordinary users will continue to authenticate themselves via the standard login mechanism.
Our production environment (hosted by a well-known company) comprises load-balanced application servers and I'm unclear as to how this set-up will handle the certificates and I'm not certain if there are any pitfalls I should be aware of. I would very appreciate some thoughts, comments or real-world advice on the subject.